From a1025dcd377ef92d9a09af03b70ce80be281ee22 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 24 Dec 2025 00:44:49 +0100 Subject: selftests: kvm: replace numbered sync points with actions Rework the guest=>host syncs in the AMX test to use named actions instead of arbitrary, incrementing numbers. The "stage" of the test has no real meaning, what matters is what action the test wants the host to perform. The incrementing numbers are somewhat helpful for triaging failures, but fully debugging failures almost always requires a much deeper dive into the test (and KVM). Using named actions not only makes it easier to extend the test without having to shift all sync point numbers, it makes the code easier to read. [Commit message by Sean Christopherson] Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/x86/amx_test.c | 88 +++++++++++++++--------------- 1 file changed, 43 insertions(+), 45 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/x86/amx_test.c b/tools/testing/selftests/kvm/x86/amx_test.c index f4ce5a185a7d..3de4402ac17d 100644 --- a/tools/testing/selftests/kvm/x86/amx_test.c +++ b/tools/testing/selftests/kvm/x86/amx_test.c @@ -124,6 +124,14 @@ static void set_tilecfg(struct tile_config *cfg) } } +enum { + /* Check TMM0 against tiledata */ + TEST_COMPARE_TILEDATA = 1, + + /* Full VM save/restore */ + TEST_SAVE_RESTORE = 2, +}; + static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, struct tile_data *tiledata, struct xstate *xstate) @@ -131,20 +139,20 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, GUEST_ASSERT(this_cpu_has(X86_FEATURE_XSAVE) && this_cpu_has(X86_FEATURE_OSXSAVE)); check_xtile_info(); - GUEST_SYNC(1); + GUEST_SYNC(TEST_SAVE_RESTORE); /* xfd=0, enable amx */ wrmsr(MSR_IA32_XFD, 0); - GUEST_SYNC(2); + GUEST_SYNC(TEST_SAVE_RESTORE); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == 0); set_tilecfg(amx_cfg); __ldtilecfg(amx_cfg); - GUEST_SYNC(3); + GUEST_SYNC(TEST_SAVE_RESTORE); /* Check save/restore when trap to userspace */ __tileloadd(tiledata); - GUEST_SYNC(4); + GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); __tilerelease(); - GUEST_SYNC(5); + GUEST_SYNC(TEST_SAVE_RESTORE); /* * After XSAVEC, XTILEDATA is cleared in the xstate_bv but is set in * the xcomp_bv. @@ -154,6 +162,8 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILE_DATA)); GUEST_ASSERT(xstate->header.xcomp_bv & XFEATURE_MASK_XTILE_DATA); + /* #NM test */ + /* xfd=0x40000, disable amx tiledata */ wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILE_DATA); @@ -166,13 +176,13 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILE_DATA)); GUEST_ASSERT((xstate->header.xcomp_bv & XFEATURE_MASK_XTILE_DATA)); - GUEST_SYNC(6); + GUEST_SYNC(TEST_SAVE_RESTORE); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA); set_tilecfg(amx_cfg); __ldtilecfg(amx_cfg); /* Trigger #NM exception */ __tileloadd(tiledata); - GUEST_SYNC(10); + GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); GUEST_DONE(); } @@ -180,18 +190,18 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, void guest_nm_handler(struct ex_regs *regs) { /* Check if #NM is triggered by XFEATURE_MASK_XTILE_DATA */ - GUEST_SYNC(7); + GUEST_SYNC(TEST_SAVE_RESTORE); GUEST_ASSERT(!(get_cr0() & X86_CR0_TS)); GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILE_DATA); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA); - GUEST_SYNC(8); + GUEST_SYNC(TEST_SAVE_RESTORE); GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILE_DATA); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA); /* Clear xfd_err */ wrmsr(MSR_IA32_XFD_ERR, 0); /* xfd=0, enable amx */ wrmsr(MSR_IA32_XFD, 0); - GUEST_SYNC(9); + GUEST_SYNC(TEST_SAVE_RESTORE); } int main(int argc, char *argv[]) @@ -244,6 +254,7 @@ int main(int argc, char *argv[]) memset(addr_gva2hva(vm, xstate), 0, PAGE_SIZE * DIV_ROUND_UP(XSAVE_SIZE, PAGE_SIZE)); vcpu_args_set(vcpu, 3, amx_cfg, tiledata, xstate); + int iter = 0; for (;;) { vcpu_run(vcpu); TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); @@ -253,20 +264,9 @@ int main(int argc, char *argv[]) REPORT_GUEST_ASSERT(uc); /* NOT REACHED */ case UCALL_SYNC: - switch (uc.args[1]) { - case 1: - case 2: - case 3: - case 5: - case 6: - case 7: - case 8: - fprintf(stderr, "GUEST_SYNC(%ld)\n", uc.args[1]); - break; - case 4: - case 10: - fprintf(stderr, - "GUEST_SYNC(%ld), check save/restore status\n", uc.args[1]); + ++iter; + if (uc.args[1] & TEST_COMPARE_TILEDATA) { + fprintf(stderr, "GUEST_SYNC #%d, check TMM0 contents\n", iter); /* Compacted mode, get amx offset by xsave area * size subtract 8K amx size. @@ -279,11 +279,25 @@ int main(int argc, char *argv[]) ret = memcmp(amx_start, tiles_data, TILE_SIZE); TEST_ASSERT(ret == 0, "memcmp failed, ret=%d", ret); kvm_x86_state_cleanup(state); - break; - case 9: - fprintf(stderr, - "GUEST_SYNC(%ld), #NM exception and enable amx\n", uc.args[1]); - break; + } + if (uc.args[1] & TEST_SAVE_RESTORE) { + fprintf(stderr, "GUEST_SYNC #%d, save/restore VM state\n", iter); + state = vcpu_save_state(vcpu); + memset(®s1, 0, sizeof(regs1)); + vcpu_regs_get(vcpu, ®s1); + + kvm_vm_release(vm); + + /* Restore state in a new VM. */ + vcpu = vm_recreate_with_one_vcpu(vm); + vcpu_load_state(vcpu, state); + kvm_x86_state_cleanup(state); + + memset(®s2, 0, sizeof(regs2)); + vcpu_regs_get(vcpu, ®s2); + TEST_ASSERT(!memcmp(®s1, ®s2, sizeof(regs2)), + "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx", + (ulong) regs2.rdi, (ulong) regs2.rsi); } break; case UCALL_DONE: @@ -293,22 +307,6 @@ int main(int argc, char *argv[]) TEST_FAIL("Unknown ucall %lu", uc.cmd); } - state = vcpu_save_state(vcpu); - memset(®s1, 0, sizeof(regs1)); - vcpu_regs_get(vcpu, ®s1); - - kvm_vm_release(vm); - - /* Restore state in a new VM. */ - vcpu = vm_recreate_with_one_vcpu(vm); - vcpu_load_state(vcpu, state); - kvm_x86_state_cleanup(state); - - memset(®s2, 0, sizeof(regs2)); - vcpu_regs_get(vcpu, ®s2); - TEST_ASSERT(!memcmp(®s1, ®s2, sizeof(regs2)), - "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx", - (ulong) regs2.rdi, (ulong) regs2.rsi); } done: kvm_vm_free(vm); -- cgit v1.2.3 From 0383a8edef396cf0a6884b0be81d62bde60737b0 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 31 Dec 2025 16:47:26 +0100 Subject: selftests: kvm: try getting XFD and XSAVE state out of sync The host is allowed to set FPU state that includes a disabled xstate component. Check that this does not cause bad effects. Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/x86/amx_test.c | 38 +++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 8 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/x86/amx_test.c b/tools/testing/selftests/kvm/x86/amx_test.c index 3de4402ac17d..bee56c1f7833 100644 --- a/tools/testing/selftests/kvm/x86/amx_test.c +++ b/tools/testing/selftests/kvm/x86/amx_test.c @@ -125,11 +125,17 @@ static void set_tilecfg(struct tile_config *cfg) } enum { + /* Retrieve TMM0 from guest, stash it for TEST_RESTORE_TILEDATA */ + TEST_SAVE_TILEDATA = 1, + /* Check TMM0 against tiledata */ - TEST_COMPARE_TILEDATA = 1, + TEST_COMPARE_TILEDATA = 2, + + /* Restore TMM0 from earlier save */ + TEST_RESTORE_TILEDATA = 4, /* Full VM save/restore */ - TEST_SAVE_RESTORE = 2, + TEST_SAVE_RESTORE = 8, }; static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, @@ -150,7 +156,16 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, GUEST_SYNC(TEST_SAVE_RESTORE); /* Check save/restore when trap to userspace */ __tileloadd(tiledata); - GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); + GUEST_SYNC(TEST_SAVE_TILEDATA | TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); + + /* xfd=0x40000, disable amx tiledata */ + wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILE_DATA); + + /* host tries setting tiledata while guest XFD is set */ + GUEST_SYNC(TEST_RESTORE_TILEDATA); + GUEST_SYNC(TEST_SAVE_RESTORE); + + wrmsr(MSR_IA32_XFD, 0); __tilerelease(); GUEST_SYNC(TEST_SAVE_RESTORE); /* @@ -210,10 +225,10 @@ int main(int argc, char *argv[]) struct kvm_vcpu *vcpu; struct kvm_vm *vm; struct kvm_x86_state *state; + struct kvm_x86_state *tile_state = NULL; int xsave_restore_size; vm_vaddr_t amx_cfg, tiledata, xstate; struct ucall uc; - u32 amx_offset; int ret; /* @@ -265,20 +280,27 @@ int main(int argc, char *argv[]) /* NOT REACHED */ case UCALL_SYNC: ++iter; + if (uc.args[1] & TEST_SAVE_TILEDATA) { + fprintf(stderr, "GUEST_SYNC #%d, save tiledata\n", iter); + tile_state = vcpu_save_state(vcpu); + } if (uc.args[1] & TEST_COMPARE_TILEDATA) { fprintf(stderr, "GUEST_SYNC #%d, check TMM0 contents\n", iter); /* Compacted mode, get amx offset by xsave area * size subtract 8K amx size. */ - amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE; - state = vcpu_save_state(vcpu); - void *amx_start = (void *)state->xsave + amx_offset; + u32 amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE; + void *amx_start = (void *)tile_state->xsave + amx_offset; void *tiles_data = (void *)addr_gva2hva(vm, tiledata); /* Only check TMM0 register, 1 tile */ ret = memcmp(amx_start, tiles_data, TILE_SIZE); TEST_ASSERT(ret == 0, "memcmp failed, ret=%d", ret); - kvm_x86_state_cleanup(state); + } + if (uc.args[1] & TEST_RESTORE_TILEDATA) { + fprintf(stderr, "GUEST_SYNC #%d, before KVM_SET_XSAVE\n", iter); + vcpu_xsave_set(vcpu, tile_state->xsave); + fprintf(stderr, "GUEST_SYNC #%d, after KVM_SET_XSAVE\n", iter); } if (uc.args[1] & TEST_SAVE_RESTORE) { fprintf(stderr, "GUEST_SYNC #%d, save/restore VM state\n", iter); -- cgit v1.2.3 From 3611ca7c12b740e250d83f8bbe3554b740c503b0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 29 Dec 2025 12:23:30 -0800 Subject: selftests: kvm: Verify TILELOADD actually #NM faults when XFD[18]=1 Rework the AMX test's #NM handling to use kvm_asm_safe() to verify an #NM actually occurs. As is, a completely missing #NM could go unnoticed. Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/x86/amx_test.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/x86/amx_test.c b/tools/testing/selftests/kvm/x86/amx_test.c index bee56c1f7833..37b166260ee3 100644 --- a/tools/testing/selftests/kvm/x86/amx_test.c +++ b/tools/testing/selftests/kvm/x86/amx_test.c @@ -69,6 +69,12 @@ static inline void __tileloadd(void *tile) : : "a"(tile), "d"(0)); } +static inline int tileloadd_safe(void *tile) +{ + return kvm_asm_safe(".byte 0xc4,0xe2,0x7b,0x4b,0x04,0x10", + "a"(tile), "d"(0)); +} + static inline void __tilerelease(void) { asm volatile(".byte 0xc4, 0xe2, 0x78, 0x49, 0xc0" ::); @@ -142,6 +148,8 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, struct tile_data *tiledata, struct xstate *xstate) { + int vector; + GUEST_ASSERT(this_cpu_has(X86_FEATURE_XSAVE) && this_cpu_has(X86_FEATURE_OSXSAVE)); check_xtile_info(); @@ -195,17 +203,13 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg, GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA); set_tilecfg(amx_cfg); __ldtilecfg(amx_cfg); - /* Trigger #NM exception */ - __tileloadd(tiledata); - GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); - GUEST_DONE(); -} + /* Trigger #NM exception */ + vector = tileloadd_safe(tiledata); + __GUEST_ASSERT(vector == NM_VECTOR, + "Wanted #NM on tileloadd with XFD[18]=1, got %s", + ex_str(vector)); -void guest_nm_handler(struct ex_regs *regs) -{ - /* Check if #NM is triggered by XFEATURE_MASK_XTILE_DATA */ - GUEST_SYNC(TEST_SAVE_RESTORE); GUEST_ASSERT(!(get_cr0() & X86_CR0_TS)); GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILE_DATA); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA); @@ -217,6 +221,11 @@ void guest_nm_handler(struct ex_regs *regs) /* xfd=0, enable amx */ wrmsr(MSR_IA32_XFD, 0); GUEST_SYNC(TEST_SAVE_RESTORE); + + __tileloadd(tiledata); + GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE); + + GUEST_DONE(); } int main(int argc, char *argv[]) @@ -253,9 +262,6 @@ int main(int argc, char *argv[]) vcpu_regs_get(vcpu, ®s1); - /* Register #NM handler */ - vm_install_exception_handler(vm, NM_VECTOR, guest_nm_handler); - /* amx cfg for guest_code */ amx_cfg = vm_vaddr_alloc_page(vm); memset(addr_gva2hva(vm, amx_cfg), 0x0, getpagesize()); -- cgit v1.2.3